Surgical sponges



United States Patent() 3,974,496 SRGCAL SFNGES Fatti Nuineio, ighlandPark, and Gordon Lindenhlad, Township, Nd., assignors to @lin MathiesonChemical orporation, New York, NX., a corporation oi Virginia NoBrewing. Filed June 16, i959, Ser. No. Silul 3 Claims. till. l--d) Thisinvention relates to improved surgical Sponges and the preparationthereof.

The location and recovery of surgical Sponges (i.e., sterile pads ofabsorbent material used to absorb body iluids which tend to collect andthus interfere With the erformance of successful operative procedures)is a problem which is as old as the operative procedures themselves. Theproblem is made more difficult by the tendency of the Sponges to becomecamoul'laged through absorption o the colored body fluids therebydiminishing the usefulness of the visual faculties in detecting them.Attempts have been made to solve the problem by maintaining a carefulcount of the Sponges that are used and comparing it with the count ofthe Sponges which are discarded. 1further attempts at solution have beenmade by using metal-wired sponges which can be located by X-ray. Neitherthe tally method, nor the X-ray method has been an ideal solution sincein the case of the former human fraility often leads to improper counts,and in the case of the latter, the use of X-rays results in unwanteddelays towards tne completion of operative procedures While awaiting thedeveloped X-ray pictures, and necessitates the presence in the operatingroom of the cumbersome and expensive X-ray equipment.

lt is the object ot this invention to overcome the deliciencies of theart by the provision of surgical Sponges having affine thereto withsuilicient permanence to resist leaching by the body fluids, a non-toxicquantity of a radioactive labeling agent sufdcient to render the labeledsponge easily detectable by conventional scintillation counters.

ln accordance With the method of this invention, the labeled Sponges areprepared by contacting pieces of absorbent material of suitable size tobe useful as surgical Sponges, with a radioactive labeling agent, andsubjecting them to conditions of heat and pressure for a time su'icientto assure sterilization.

Unexpectedly it has been found that the single step of autoclaving theimpregnated sponge until it is sterilized yields, not only a spongeWhich is surgically sterile, but one which contains a labeling agentailhred With such permanence that it remains aixed to the sponge even inthe presence of body fluids in which the labeling agents per se aresoluble. The sterilized labeled sponge thus prepared can be used in themanner prescribed for ordinary unlabeled surgical Sponges.

The absorbent material suitable for use herein can be any substancewhich is normally used as a surgical sponge. Cotton gauge pads, beingreadily available and highly economical, are preferred.

The labeling agents suitable for the practice of this invent-ion mustcontain, preferably in chemically combined form, a metallic ornon-metallic radioactive isotope which is non-toxic in quantities whichare suieiently radioactive lto percepti'oly register on conventionalcrystal scintillation counting equipment. Thus, in the proper amount, itmust be able to register a count which is at least two, and optimally atleast rive times the count being continually registered by the ambientradiation normally existing in the atmospheric background. Preferredisotopes are those which have a hall life greater than one Week and lessthan two months and emit primarily gamice .ma radiation. The isotopesmay form, or be a part of, either the anion or the cation of thecompound which constitutes the labeling agent. The isotope may bechemically combined as a simple ion resulting from the loss or gain ofelectrons, or in the form of a complex ion such as the chromate ion.Among the preferred radioactive isotopes may be mentioned inter alia:radioactive halogens such -as 1131; radioactive alkaline earth metalssuch as Bali0 and Ca47; radioactive alkali metals such as Rb; andradioactive heavy metals such as those of the iron period (e0. Cr51,Mnz, 21165 and Fe59); and those of the silver period (eg. Ag105, Agl6and Cd115).

The labeling agent is most conveniently applied to the surgical spongein the form of a dilute solution of the radioactive chemical compound ina liquid medium. The liquid medium may be chosen from a Wide range oforganic solvents and inorganic solvent which will dissolve theradioactive compound to be used as the labeling agent. useful solvent itis preferred as the liquid medium for Water soluble labeling agents. Toprepare the solution it is only necessary to dissolve the radioactivematerial in the Water. This may in most cases be accomplished at roomtemperatures, but may be hastened in others by the application of heat.Among the labeling agents Which may be formed with the foregoingradioactive isotopes there may be named *sodium chromate (it indicatesthe radioactive moiety), *calcium iodide, *barium carbonate, zinc"chloride, ferrous ilsulfate, ferric itchloride, cadmium *sulfate andsilver *nitrate The proper concentration of the radioactive material inthe solution will depend on the amount of solution to be used intreating each sponge. Suliicient solution should be used for each spongeto assure that the sponge will be suiiiciently radioactive to register acount of at least twice, and optimally etween live and ten times thebackground count on a crystal scintillation counter.

In order to prepare the labeled surgical Sponges of this invention aconventional sponge is treated with a quantity of a solution of theradioactive labeling agent, as defined above. The labeling agent is thenaixed to the sponge by subjecting it to heat and/ or pressure (eg.autoclaving) for a time sufficient to at least sterilize the sponge.Conventional hospital autoclaving equipment is suitable for theperformance of this step. Suitable results are obtained by heating thesponge at 250 F. and l5 p.s.i. for a period of l5 minutes.rl`e1riperature, pressure and length of heating step may be varied solong as the selected conditions will yield properly sterilized Sponges.

The Sponges thus produced are used as the conventional unlabeledSponges. They should be used Within a short period following preparationin order to insure that decay of the labeling agent does not proceed tothe point at Which the labeled Sponges are not suticiently radioactiveto energize the conventional crystal scintillation counting equipmentwhich is to be used to locate the sponge.

Aft-er use, the Sponges may be discarded through the usual radioactiveWaste disposal facilities.

The following example is presented to more fully illustrate theinvention.

EXAMPLE A. Preparation of Sodium Chromate Solution A glass vesselcontaining dilute solution of chromic chloride (l0 ml.) having aspeciiic activity of l0 millicuries/mg. is immersed in an ice-salt waterbath and chilled to below 4 C. 2 N. sodium hydroxide is added to thechilled solution dropwise, with stirring until a light blue opalescentprecipitate appears. The dropwise Since Water is the most readilyavailable yand addition is continued until the precipitate dissolves.Hydrogen peroxide (30%) is added dropwise until the light blue-greencolor changes .to yellow and the solution is removed from the Water bathand boiled to remove the B. Preparation of Labeled Surgical Sponges A(conventional cotton gauze surgical sponge measuring Z n 2" is treatedwith 0.1 ml.y of the solution prepared in step A. The treated sponge IisWrapped in absorbent paper and placed in an autoclave which isadjust'edY to maintain a pressure of 15 p.s.i. at `a temperature of 250F. The spongeY is removed from the autoclave and tested for specificactivity. It shows a radio# activity'of 1.2 microcuries.

In order to show the usefulness of the Sponges of this invention asponge prepared as in step B was implanted in a large dog. The spongeexhibited sucient radioactivity to be easily detectable by aconventional crystal scintillation counter. lThe urine of the dog testednegative 24 hours for radioactive material, and gross lscintilla- 'tionscanningv of` the animal .indicated no translocation of radioactivitythroughout the animal. The tests show that the radioactive moiety hadbeen permanently fixed to the sponge by autoclaving.

Eollov'ving the exemplied procedure, surgical sponges l. A process ofpreparing a surgical sponge having a radioactive labeling agentpermanently affixed thereto and impregnated thereon, which comprisestreating an absorbent material wvith a solution of a radioactivelabeling `agent until a non-toxic quantity of said agent is absorbed andthen heating the absorbent material for a time and under conditionsSucient to permanently aix the radioactive labeling agent to theabsorbent material'and to assure sterilization,

2. A process'of aixing a radioactive labeling Yagent to a `surgicalsponge, vwhich comprises treating a surgical cotton sponge with asolution of a radioactive labeling agent until 4a non-toxic quantity ofsaid agent is absorbed on said sponge and then autoclaving the spongefor a time suiicient to permanently Aaiiix the radioactive labelingagent to the sponge and to assure sterilization of the sponge.

'3. The process of claim 2 in which the labeling agent is sodiumradioactive chromate.

References Cited in the le of this patentV UNITED STATES PATENTS

1. A PROCESS OF PREPARING A SURGICAL SPONGE HAVING A RADIACTIVE LABELINGAGENT PERMANENTLY AFFIXED THERETO AND IMPREGATED THEREON, WHICHCOMPRISES TREATING AN ABSORBENT MATERIAL WITH A SOLITION OF ARADIOACTIVE LABELING AGENT UNTIL A NON-TOXIC QUANTITY OF SAID AGENT ISABSORBED AND THEN HEATING THE ABSORBENY MATERIAL FOR A TIME AND UNDERCONDITIONS SUFFICIENT TO PERMANENTLY AFFIX THE RADIOACTIVE LABELINGAGENT TO THE ABSORBENT MATERIAL AND TO ASSURE STERILIZATION.